I am not sure what is going on with your child but it reminded me of a conversation I had with our daughter at this age.
She was an early talker and I talk a lot. When she was young I almost kept an ongoing conversation going on while around her explaining what I was doing, giving her the words for what she was doing..
Anyway at about the age of 4 or 5 we were int he car and she was just talking and talking and I could not concentrate on my driving. I finally turned to her and said. "You know what? I do not think I have ever told you this, but we do not have to talk at every moment. Sometimes it is just fun to be together and just share the time." It was like I had given her permission to just be quiet and enjoy just being.
She actually has used this line on me a few times.. stinker...
Maybe you can do the same for your daughter. Free her by saying, I know that you love me, you know I love you, when you say it so much it makes me feel like you do not believe me. Do you believe I love you? Do you believe that I know you love me?
The talking in the movie.. is another issue. I am sure you already do this, but for every event church, inside stores, movies, restaurants, visiting someones home before entering the building at this age I would ask my daughter to repeat the rules for this event. She would say, "hands behind my back, inside voice, only walking, no talking, no buying snacks, go to the potty before we sit down", whatever were our rules for behavior for the event. I would always tell her "thank you for reminding me"..